Anionic polymerization initiators containing adducts of cyclic secondary amines and conjugated dienes, and products therefrom

ABSTRACT

An anionic polymerization initiator includes a carbon-lithio salt of the adduct of a cyclic secondary amine with a conjugated diene. A method of preparing an anionic polymerization initiator includes reacting an excess of a cyclic secondary amine with a conjugated diene to form an adduct; and, reacting the adduct with an organolithium compound. A method of preparing a polymer includes forming a solution of one or more anionically polymerizable monomers in a hydrocarbon solvent; and, polymerizing the monomer with an anionic polymerization initiator comprising a carbon-lithio salt of the adduct of a cyclic secondary amine with a conjugated diene. A functionalized polymer includes the termination product of a living polymer having the general formula AYLi, wherein A is a functional group derived from an anionic polymerization initiator; and, Y is a divalent polymer radical; wherein the anionic polymerization initiator is a carbon-lithio salt of the adduct of a cyclic secondary amine with a conjugated diene.

This application is a division of application Ser. No. 08/175,294, filedDec. 29, 1993 now U.S. Pat. No. 5,491,230.

TECHNICAL FIELD

The subject invention relates to anionic polymerization resulting indiene polymer and copolymer elastomers. More particularly, the presentinvention relates to polymerization employing an initiator which is theC-lithio salt of the diene adducts of cyclic secondary amines. Theresulting polymers are chain-end modified and exhibit reduced hysteresischaracteristics.

BACKGROUND OF THE INVENTION

In the art it is desirable to produce elastomeric compounds exhibitingreduced hysteresis. Such elastomers, when compounded to form articlessuch as tires, power belts and the like, will show an increase inrebound, a decrease in rolling resistance and will have less heatbuild-up when mechanical stresses are applied.

Previous attempts at preparing reduced hysteresis products have includedhigh temperature mixing of the filler-rubber mixtures in the presence ofselectively-reactive promoters to promote compounding materialreinforcement; surface oxidation of the compounding materials; chemicalmodifications to the terminal end of polymers usingtetramethyldiaminobenzophenone (Michler's ketone), tin coupling agentsand the like and surface grafting thereon.

It has also been recognized that carbon black, employed as a reinforcingfiller in rubber compounds, should be well dispersed throughout therubber in order to improve various physical properties. One example ofthe recognition is provided in published European Pat. Appln. EP 0 316255 A2 which discloses a process for end capping polydienes by reactinga metal terminated polydiene with a capping agent such as a halogenatednitrile, a heterocyclic aromatic nitrogen containing compound or analkyl benzoate. Additionally, the application discloses that both endsof the polydiene chains can be capped with polar groups by utilizingfunctionalized initiators, such as lithium amides.

Organolithium polymerization initiators are also known in the art. U.S.Pat. No. 3,439,049 discloses an organolithium initiator prepared from ahalophenol in a hydrocarbon medium.

U.S. Pat. No. 4,015,061 is directed toward amino-functional initiatorswhich polymerize diene monomers to form mono- or di-primary arylamine-terminated diene polymers upon acid hydrolysis.

U.S. Pat. No. 4,935,471 discloses dicapped polymers obtained usingcertain N-Li initiators, including piperidinyl and pyrrolidinyloligoalkylamino lithiums. It has been found that piperidine-basedinitiators result in polymers having inferior interaction withcompounding materials such as carbon black, and hence, result in littleif any reduction in the hysteresis characteristics of the polymers. Ithas further been found that pyrrolidine-based polymers have a strong andoffensive odor, making their use commercially undesirable.

The present invention provides novel initiators for anionicpolymerization which become incorporated into the polymer chainproviding a functional group which greatly improves the dispersabilityof carbon black throughout the elastomeric composition duringcompounding. As will be described hereinbelow, these initiators are aproduct of the reaction between the diene adducts of cyclic Secondaryamines and an organolithium compound.

SUMMARY OF INVENTION

It is therefore, an object of the present invention to provide ananionic polymerization initiator.

It is another object of the present invention to provide an initiator asabove, which when employed to polymerize an anionically polymerizablemonomer, will result in a polymer having reduced hysteresischaracteristics.

It is yet another object of the present invention to provide productsprepared using the anionic polymerization initiators as above.

It is still another object to provide a method for the preparation of ananionic polymerization initiator as above, and polymer productstherefrom.

At least one or more of the foregoing objects, together with theadvantages thereof over the known art relating to anionic polymerizationinitiators, which shall become apparent from the specification whichfollows, are accomplished by the invention as hereinafter described andclaimed.

In general the present invention provides an anionic polymerizationinitiator which comprises a carbon-lithio salt of the adduct of a cyclicsecondary amine with a conjugated diene.

There is also provided according to the invention, a method of preparingan anionic polymerization initiator which comprises reacting an excessof a cyclic secondary amine with a conjugated diene to form an adduct;and, reacting the adduct with an organolithium compound.

A method of preparing a polymer comprises forming a solution of one ormore anionically polymerizable monomers in a hydrocarbon solvent; and,polymerizing the monomer with an anionic polymerization initiatorcomprising a carbon-lithio salt of the adduct of a cyclic secondaryamine with a conjugated diene.

A functionalized polymer comprises the termination product of a livingpolymer having the general formula AYLi, wherein A is a functional groupderived from an aminoalkenyl anionic polymerization initiator; and, Y isa divalent polymer radical; wherein the artionic polymerizationinitiator is a carbon-lithio salt of the adduct of a cyclic secondaryamine with a conjugated diene.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

As will become apparent from the description which follows, the presentinvention provides novel initiators for artionic polymerization of dienehomopolymer and copolymer elastomers. Polymers prepared with theseinitiators contain a functional terminal group and it has beendiscovered herein that vulcanizable elastomeric compounds and articlesthereof based upon such functionally terminated polymers exhibit usefulproperties, particularly reduced hysteresis. Hysteresis is generallyknown as the failure of a properly that has been changed by an externalagent to return to its original value when the cause of the change isremoved. When compounded to make products such as tires, power belts andthe like, the polymeric products according to the invention, exhibitincreased rebound, decreased rolling resistance and less heat build-upduring periods of applied mechanical stress.

The present invention provides an anionic polymerization initiator whichis a carbon-lithio salt of the adduct of a cyclic secondary amine with aconjugated diene, such as a 1,3-diene, and products resulting frompolymerization utilizing such an initiator. Generally, the initiator isprepared by first forming the adduct of a cyclic secondary amine withthe conjugated diene and then reacting the adduct with an organolithiumcompound preferably in the presence of a donor solvent. The resultinginitiator is used to prepare any anionically-polymerized elastomer,e.g., polybutadiene, polyisoprene, polystyrene and the like, andcopolymers thereof with monovinyl aromatics such as styrene, alphamethyl styrene and the like, or trienes such as myrcene. Thus, theelastomers include diene homopolymers and copolymers thereof withmonovinyl aromatic polymers. Suitable monomers for polymerizationemploying the initiators according to the present invention includeconjugated dienes having from about 4 to about 12 carbon atoms andmonovinyl aromatic monomers having 8 to 18 carbon atoms and trienes, andmixtures thereof. Examples of such conjugated diene monomers and thelike useful in the present invention include 1,3-butadiene, isoprene,1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and 1,3-hexadiene, andaromatic vinyl monomers include styrene, α-methylstyrene,p-methylstyrene, vinyltoluene and vinylnaphthalene. The conjugated dienemonomer and aromatic vinyl monomer are normally used at the weightratios of 95-50:5-50, preferably 85-55:15-45. It is most preferred thatthe polymer have a high styrene content, that is, a styrene content ofabout 20 percent by weight or more. The resulting polymers may also befurther end-capped with a suitable reagent, as will be more fullydiscussed hereinbelow.

By "adduct" as used herein, it is meant the product or mixture ofproducts arising from the addition of a secondary amine of the inventionwith an equimolar amount of a conjugated diene of the invention, suchthat the nitrogen of the secondary amine becomes bonded to a carbon ofthe conjugated diene. Although products of 1,4- or 4,1- additionpredominate, resulting in cis- and/or trans-1-amino-2-alkenes, productsof 1,2-, 2,1- and/or 3,4-addition may also be present in the mixture.

By "donor solvent" as used herein, it is meant a solvent having in itsstructure a heteroatom with one or more pairs of nonbonded electrons.These types of solvents can coordinate with electron-deficient speciessuch as lithium, by "donating" their nonbonded paris of electrons, thussolvating the lithium species and reducing their state of aggregation.Such solvents include various ethers and tertiary amine compounds, suchas tetrahydrofuran, glycol ethers, triethylamine,N,N,N',N'-tetramethylethylenediamine, and the like.

According to the present invention, novel compositions are produced inwhich the products are prepared by polymerization from the lithium saltsof the diene adducts of secondary amines. This will result in afunctional group or unit derived from the initiator being incorporatedat the head of the polymer chain that will have unshared electron pairs.That is, it is a Lewis base. The unshared electrons can bind to Lewisacids elsewhere in the system, such as for example, to carbon black inthe composition. These polymers may be useful as reduced hysteresismaterials when so compounded. The initiators according to the inventioninclude lithium compounds which are the C-metalation products oftertiary amines. That is, they are the product of replacement of C--H byC--Li. For purposes of describing this invention, such C--Li compoundsare called carbon-lithio salts. More specifically, the amines arehydrocarbon amines, and the lithium salts are amine-containingorganolithium compounds.

The secondary amines useful in the preparation of the adducts accordingto the invention, include cyclic secondary amines having from about 6 toabout 16 methylene groups. Preferred cyclic secondary amines arehexamethyleneimine, heptamethyleneimine and dodecamethyleneimine. Theseamines substituted with a substituent group are also within the scope ofthe invention. Such a substituent group may include for example,dialkylaminos, dialkylaminoalkyls, alkyls, alkenyls, cycloalkyls,cycloalkenyls, bicycloalkyls, bicycloalkenyls and aralkyls, andnon-interfering O-, S- and N-containing analogues thereof, where alkylis as described below.

Other useful amines include azetidine; pyrrolidine; piperidine;morpholine; and, N-alkyl piperazines.

Examples of conjugated dieties useful in the practice of the presentinvention include 1,3-dienes having from about 4 to about 20 carbonatoms. Two preferred dienes are 1,3-butadiene and isoprene. Othersinclude piperylene, myrcene, 1,3-hexadiene, 1,3-cyclohexadiene,1,3-cycloheptadiene, 1,3-cyclooctadiene, 2,4-hexadiene, 1,3-decadiene,and various alkylbutadienes where alkyl is as described below.

The adduct intermediate thus prepared is then reacted with anorganolithium compound, RLi, where R is selected from alkyls,cycloalkyls, alkenyls, aryls and aralkyls having from 1 to about 20carbon atoms and short chain length low molecular weight polymers fromdiolefin and vinyl aryl monomers having up to about 25 units. Typicalalkyls include n-butyl, s-butyl, methyl, ethyl, isopropyl and the like.The cycloalkyls include cyclohexyl, menthyl and the like. The alkenylsinclude allyl, vinyl and the like. The aryl and aralkyl groups includephenyl, benzyl, oligo(styryl) and the like. Exemplary short chain lengthpolymers include the oligo(butadienyls), oligo(isoprenyls),oligo(styryls) and the like. Alkyllithiums are preferred.

The preferred initiators according to the invention are the reactionproducts of an organolithium compound with the conjugated diene and theamine adduct, as such reactants are discussed hereinabove, wherein thelithio carbon is also bonded to two hydrogen atoms to form a primarycarbon-lithio salt, --CH₂ --Li. Three preferred initiators according tothe present invention include (i) the C-lithio salt of the adduct ofhexamethyleneimine and 1,3-butadiene, which is represented by theformula ##STR1## (ii) the C-lithio salt of the adduct ofhexamethyleneimine and isoprene, represented by the formulae ##STR2##and, (iii) the C-lithio salt of the adduct of dodecamethyleneimine andbutadiene, represented by the formula ##STR3##

It will be appreciated that the lithium atom in each of the formulaeprovided herein may be at a different location in the molecule and stillbe within the scope of the invention.

To prepare the adduct of the invention, an equal or excess amount of thecyclic secondary amine is added to the diene, such as from about 1 toabout 10 moles of amine per mole of the diene, as will be exemplifiedhereinbelow. The reaction is preferably catalyzed by the addition of analkyllithium to the amine before the introduction of the diene. After asuitable reaction period, such as from about 1 to about 16 hours, theadduct is isolated by conventional techniques, such as by removing theexcess amine by distillation, and then further purifying the adduct bydistillation, recrystallization or the like. The adduct preferablypredominantly includes one mole of amine per one mole of diene, althoughother proportions are also within the scope of the invention.

The C-lithio salts of these adducts may be prepared under a variety ofconditions using various hydrocarbon solvents. Preferably, the solventsare those useful in anionic polymerizations, and/or polar solvents asmay be desirable for improved solubility of the lithio salt or theadduct, provided that the solvents are compatible with anionicpolymerizations and the subsequent polymer recovery and dryingprocedures. Examples of useful solvents include hexane and cyclohexane.

In one preferred embodiment of the present invention, the initiator isthe lithium salt of N-(1-but-2-enyl)hexamethyleneimine, generated by thereaction of a mixture of one equivalent ofN-(1-but-2-enyl)hexamethyleneimine with about one equivalent ofn-butyllithium, in hexanes, cyclohexane or mixtures thereof, in thepresence of about 0.5 to about 1 equivalent of the donor solventN,N,N',N'-tetramethyethylenediamine (TMEDA), at from about -80° C. toabout 100° C., for from about 1 minute to several days. Preferredreaction conditions include a reaction time of from about 30 minutes toabout 24 hours, at a temperature of about 20° C. to about 50° C.

Other useful donor solvents include, for example, tetrahydrofuran (THF);ethers such as 1,2-dimethoxyethane, oligomeric oxolanyl propanes, crownethers and the like; and, tertiary mines such as triethylamine, TMEDA,N-methylpyrrolidine, 1,1,4,7,7-pentamethyldiethylenetriamine,1,2-dipiperidinoethane, and the like.

The initiators according to the present invention may optionally betreated with from about 1 to about 500 equivalents of a monomer beforethe main polymerization or co-polymerization, is made. However, thisstep is not an absolute limitation of the invention.

As stated above, the resulting initiators may be employed to polymerizeany anionically polymerizable monomer, such as butadiene, isoprene,styrene, myrcene or the like. Suitable polymerization modifiers may alsobe employed, such as ethers or amines, to provide the desiredmicrostructure and randomization of the comonomer units. The molecularweight of the polymer produced is preferably such that a proton-quenchedsample will exhibit a gum-Mooney (ML/4/100) of from about 1 to about150. Lower molecular weight compounds can also be made employing theinvention initiators, and which are within the scope of the invention.Such lower molecular weight polymers may have a molecular weight of fromseveral hundred to tens of thousands of mass units. These polymers canbe used as viscosity modifiers and as dispersants for particulates, suchas carbon black in oil.

The living polymers prepared using the initiators of the invention, havea functional amine group derived from the initiator compound and bondedat the initiation site. Thus, it is believed that substantially everyresulting living polymer chain has the following general formula

    AYLi

where A is the aminoalkenyl functional group derived from the initiator,and Y is a divalent polymer radical. A functionalized polymer accordingto the invention therefore, is the termination product of a livingpolymer having the general formula AYLi as described.

As briefly stated hereinabove, the living polymer can be terminated bytreatment with a proton source, such as water, or alcohol, or tintetrachloride, or other hysteresis-reducing terminating compounds whichmay contain other heteroatoms such as oxygen, nitrogen, sulfur,phosphorus, tin, non-interfering halogen, and the like. Examples ofsuitable terminators include carbon dioxide; isomeric vinylpyridines;dialkylaminobenzaldehydes; (bis)dialkylaminobenzophenone (Michler'sketones); dimethylimidazolidinone; Schiff bases and the like.

The living polymer may also be coupled by use of conventional couplingreagents, such as silicon tetrachloride or the like, to preparesymmetrically "dicapped" polymers. End-linked polymers preparedaccording to the invention, through reaction with SnCl₄, C₄ H₉ SnCl₃, orthe like, to obtain products with greater than about 10 percentend-linking through tin, are especially desirable as elastomericcompositions having reduced hysteresis characteristics.

The polymer may be recovered from the solvent by conventionaltechniques. These include steam or alcohol coagulation, thermaldesolventization, or any other suitable method. Additionally, solventmay be removed from the resulting polymer by drum drying, extruderdrying, vacuum drying or the like. Desolventization by drum-drying,coagulation in alcohol, steam or hot water desolventization, extruderdrying, vacuum drying, spray drying, and combinations thereof arepreferred. An antioxidant and/or an antiozonant compound is usuallyadded to the polymer or polymer cement at or before this stage.

The polymers of the present invention can be used alone or incombination with other elastomers to prepare an elastomer product suchas a tire treadstock, sidewall stock or other tire component stockcompound. In a tire of the invention, at least one such component isproduced from a vulcanizable elastomeric or rubber composition. Forexample, the polymers according to the invention can be blended with anyconventionally employed treadstock rubber which includes natural rubber,synthetic rubber and blends thereof. Such rubbers are well known tothose skilled in the art and include synthetic polyisoprene rubber,styrene/butadiene rubber (SBR), polybutadiene, butyl rubber, Neoprene,ethylene/propylene rubber, ethylene/propylene/diene rubber (EPDM),acrylonitrile/butadiene rubber (NBR), silicone rubber, thefluoroelastomers, ethylene acrylic rubber, ethylene vinyl acetatecopolymer (EVA), epichlorohydrin rubbers, chlorinated polyethylenerubbers, chlorosulfonated polyethylene rubbers, hydrogenated nitrilerubber, tetrafluoroethylene/propylene rubber and the like. When thepolymers of the present invention are blended with conventional rubbers,the amounts can vary widely such as between about 0-80 percent by weightof the conventional rubber with from about 100-20 percent by weight ofthe invention polymer.

The polymers can be compounded with carbon black in amounts ranging fromabout 5 to about 100 parts by weight, per 100 parts of rubber (phr),with about 5 to about 80 parts being preferred and from about 40 toabout 70 phr being more preferred. The carbon blacks may include any ofthe commonly available, commercially-produced carbon blacks but thosehaving a surface area (EMSA) of at least 20 m² /g and more preferably atleast 35 m² /g up to 200 m² /g or higher are preferred. Surface areavalues used in this application are those determined by ASTM test D-1765using the cetyltrimethyl-ammonium bromide (CTAB) technique. Among theuseful carbon blacks are furnace black, channel blacks and lamp blacks.More specifically, examples of the carbon blacks include super abrasionfurnace (SAF) blacks, high abrasion furnace (HAF) blacks, fast extrusionfurnace (FEF) blacks, fine furnace (FF) blacks, intermediate superabrasion furnace (ISAF) blacks, semi-reinforcing furnace (SRF) blacks,medium processing channel blacks, hard processing channel blacks andconducting channel blacks. Other carbon blacks which may be utilizedinclude acetylene blacks. Mixtures of two or more of the above blackscan be used in preparing the carbon black products of the invention.Typical values for surface areas of usable carbon blacks are summarizedin the following TABLE I.

                  TABLE I                                                         ______________________________________                                        CARBON BLACKS                                                                 ASTM           Surface Area                                                   Designation    (m.sup.2 /g)                                                   (D-1765-82a)   (D-3765)                                                       ______________________________________                                        N-110          126                                                            N-220          111                                                            N-339          95                                                             N-330          83                                                             N-550          42                                                             N-660          35                                                             ______________________________________                                    

The carbon blacks utilized in the preparation of the rubber compounds ofthe invention may be in pelletized form or an unpelletized flocculatedmass. Preferably, for more uniform mixing, unpelletized carbon black ispreferred. The reinforced rubber compounds can be cured in aconventional manner with known vulcanizing agents at about 0.5 to about4 phr. For example, sulfur or peroxide-based curing systems may beemployed. For a general disclosure of suitable vulcanizing agents onecan refer to Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed.,Wiley Interscience, New York 1982, Vol. 20, pp. 365-468, particularly"Vulcanization Agents and Auxiliary Materials" pp. 390-402. Vulcanizingagents may be used alone or in combination.

Vulcanizable elastomeric or rubber compositions of the invention can beprepared by compounding or mixing the polymers thereof with carbon blackand other conventional rubber additives such as fillers, plasticizers,antioxidants, curing agents and the like, using standard rubber mixingequipment and procedures and conventional amounts of such additives.

General Experimental

In order to demonstrate the preparation and properties of the initiatormixtures and elastomers according to the present invention, a number ofsuch initiators, elastomers and compounds thereof were prepared. Theinitiators were then used to polymerize styrene/butadiene mixtures, withand without end-linking, as will be demonstrated hereinbelow. Thepolymers thus prepared were then compounded and tested for hysteresis,as was a control polymer which was conventionally prepared using ann-butyllithium initiator with tin coupling. The following is a key toterms used in the Examples and Tables:

g=grams

ml=milliliters

mequiv=milliequivalent

Pzn=polymerization

i-PrOH=isopropyl alcohol

DBPC=2,6-di-tert-butyl-para-cesol

T_(g) =the glass transition temperature

EXAMPLE 1

Preparation of the adduct of hexamethyleneimine and 1,3-butadiene

A mixture ofhexamethyleneimine (49.6 g, 0.5 mol), cyclohexane (280 g),and n-butyllithium (15 ml of 1.7M solution in hexanes) was allowed tostir in a sealed container for 4 hrs. at 20°-25° C. This mixture wasthen agitated with 18.3 g (0.34 mol) of 1,3-butadiene, as anapproximately 23% solution in hexanes (78.2 g of solution), overnight at50° C. The contents of the bottle were treated with 10 ml of ethanol andthen concentrated by distillation at ambient pressure. The product wascollected in the last two cuts upon vacuum distillation at 1 Torr: a)110°-130° C., 20.8 g, and b) 120°-140° C., 30.8 g. Both cuts had thesame IR spectrum, which displayed peaks characteristic of cis andtrans-butenyl substituents at 965 and 670 cm¹.

EXAMPLE 2

Preparation of the C-lithio salt of N-(1-but-2-enyl)hexamethyleneimine

A mixture of N-(1-but-2-enyl)hexamethyleneimine, (12.2 milliequivalent(mequiv), 1.87 g, 2 ml), n-butyllithium (12.2 mequiv, 7.2 ml of a 1.7Msolution in hexanes), and N,N,N',N'-tetramethylethylenediamine ("TMEDA")(6.1 mmol, 12.2 mequiv, 3.12 ml of a 1.94M solution in hexanes) wasstirred overnight at room temperature in a sealed bottle. The resultingdark orange solution contained no unreacted n-butyllithium. It wasestimated to have a Li concentration of 0.99M, and was used directly toinitiate polymerizations.

EXAMPLE 3

Polymerization of styrene/butadiene mixtures using the C-lithio salt ofN-(1-but-2-enyl)hexamethyleneimine

Polymerizations were run using the initiator generated by lithiation inthe presence of TMEDA of the butadiene adduct of hexamethyleneimine.Table II lists the ingredients and conditions used in thepolymerizations.

A 0.99M solution of the above initiator was added to dried, sealed,nitrogen-purged bottle, through a Viton rubber cap liner, to an 80%/20%by weight blend of butadiene and styrene in hexanes, at a level of 0.85mequiv. Li/100 g monomer, and an additional amount of TMEDA was added atthe TMEDA/Li indicated in TABLE II.

                                      TABLE II                                    __________________________________________________________________________    Polymerization of Styrene/Butadiene Mixtures                                               ml of Additional                                                       Amt (g) of                                                                           1.94M TMEDA                                                                             Initiator,                                             Run No.                                                                             Monomer                                                                              (TMEDA/Li)                                                                              mequiv                                                                              Initiator, ml                                                                         Pzn temp, °C.                                                                  Pzn time, min                    __________________________________________________________________________    A     66.54    0 (0.5) 0.56  0.57    50      90                               B     67.74    0 (0.5) 0.57  0.58    50      90                               C     66.50  0.17 (1.0)                                                                              0.56  0.57    80      45                               D     67.62  0.17 (1.0)                                                                              0.57  0.58    80      45                               __________________________________________________________________________

The mixtures were agitated at 50° C. or 80° C. for 0.5 to 2.5 hrs.,proceeding to approximately 94-98% conversion to polymer. In practice,there is considerable leeway in the reaction times and temperatures,much the same as there is leeway in the reaction vessels, type ofagitation, etc., used. The treated cements then were quenched byinjection with 1.5 ml or i-PrOH, treated with an antioxidant (3 ml of amixture containing 1.6 wt % DBPC in hexane), coagulated in i-PrOH,air-dried at room temperature, then drum-dried. Suitablecharacterizations were performed. Analyses of the product polymers aregiven in Table III.

                  TABLE III                                                       ______________________________________                                        Analyses of Polymerization Products                                           SAMPLE:      A        B        C      D                                       ______________________________________                                        Polymer recovered,                                                                         94.5     94.6     97.8   95.7                                    T.sub.g, °C. (DSC, onset)                                                           -32.5    -37.5    -39.8  -41.3                                   ML/4/100, raw                                                                              31.9     99.0     34.8   100.7                                   GPC (THF):                                                                    M.sub.n      112100   199260   113560 144520                                  M.sub.w /M.sub.n                                                                           1.26     2.03     1.46   2.18                                    Comments     --       73%      --     25%                                                           coupled         coupled                                 .sup.1 H NMR (CDCl.sub.3),                                                    wt %:                                                                         Styrene      21.1     21.2     21.2   21.6                                    Block Styrene                                                                              0.7      1.4      1.3    1.7                                     1,2-         43.5     40.7     37.8   37.2                                    1,4-         35.4     38.2     40.9   41.2                                    ______________________________________                                    

EXAMPLE 4

Polymerization of butadiene and styrene with the C-iithio salt ofN-(1-but-2-enyl)hexamethyleneimine and end-linking with SnCl₄

The above procedure was followed exactly, except that after 1.5 hours ofpolymerization at 50° C., the polymerization mixture was treated with0.8 equivalent of SnCl₄ per equivalent of Li charged. The product wasworked up in the same manner as above. These showed 73% coupling in the50° C. polymerization, and 25% coupling at 80° C., which were both runafter a metalation period of approximately 24 hrs. Analyses of thesepolymers are also given in Table III.

EXAMPLE 5

Compounded evaluations of polymers made from the C-iithio salt ofN-(1-but-2-enyl)hexamethyleneimine.

The product polymers were compounded and tested as indicated in the testrecipe shown in Table V, and cured 20 minutes at 165° C. The results ofthe compounded evaluations are summarized in Table IV. These productsexhibited improved hysteresis and enhanced interaction with carbonblack, compared to unmodified elastomers. To evaluate hysteresis lossproperties, the dynamic loss factor at 50° C. (tan δ) was measured bymeans of a viscoelastometer. In general, the smaller the tan δ value,the lower the hysteresis loss.

                                      TABLE IV                                    __________________________________________________________________________    Analyses of Compounded Products                                                                                    Bound  #1 Dispersion                                                                          Dynastat, 1 Hz,          Polym. No.                                                                           Polymer      ML/4 -- Raw                                                                            ML/4 -- Cpd                                                                           Rubber, %                                                                            Index, % tan                                                                           δ 50°       __________________________________________________________________________                                                         C.                              Sn-Coupled.sup.a                                                                           74       84      36.4   91.7     0.090                           Control (BuLi initiator)                                               B      HMI--Bd.sup.b --                                                                           99       122     55.7   71.4     0.087                           Li/SnCl.sub.4, 50° C.                                           C      HMI--Bd--Li, 80° C.                                                                 35       66      33.7   96.3     0.086                    D      HMI--Bd--    101      105     48.0   70.7     0.099                           Li/SnCl.sub.4, 80° C.                                           __________________________________________________________________________     .sup.a) Sample A was not tested because its T.sub.g was significantly         higher than the others.                                                       .sup.b) HMI is hexamethyleneimine; Bd is 1,3butadiene                    

                  TABLE V                                                         ______________________________________                                        Low-Oil Test Formulation for Evaluation of Hysteresis                                            Parts per                                                             Mix     Hundred Parts                                              Ingredient Order   of Rubber                                                  ______________________________________                                        Polymer    1       100          Masterbatch:                                  Naphthenic oil                                                                           2       10           145-155° C.,                           Carbon black,                                                                            3       55           60 RPM                                        N-351                           (drop after 5 min,                            ZnO        4       3            @ 155-175° C.)                         Antioxidant                                                                              5       1                                                          Wax blend  6       2                                                          Total Masterbatch:                                                                           171                                                            Stearic acid   2            Final:                                            Sulfur         1.5          77-95° C.,                                 Accelerator    1            40 RPM                                            Total Final:   175.5                                                          ______________________________________                                    

Hence, the products according to the present invention have been shownto have similar or improved hysteresis characteristics, as compared withthe control polymer compound.

Thus, it should be evident that the initiators and products of thepresent invention are highly effective in providing elastomers andproducts having reduced hysteresis characteristics.

Based upon the foregoing disclosure, it should now be apparent that theuse of the initiators and products described herein will carry out theobjects set forth hereinabove. It is, therefore, to be understood thatany variations evident fall within the scope of the claimed inventionand thus, the selection of specific component elements can be determinedwithout departing from the spirit of the invention herein disclosed anddescribed. In particular, the adduets, reactants, monomers, terminators,solvents, methods or the like according to the present invention are notnecessarily limited to those discussed above. Thus, the scope of theinvention shall include all modifications and variations that may fallwithin the scope of the attached claims.

What is claimed is:
 1. A vulcanizable elastomer formed by compounding apolymer with from about 5 to about 80 parts by weight of carbon black,per 100 parts by weight of said polymer;wherein said polymer is preparedby polymerizing a solution of one or more anionically polymerizablemonomers in a hydrocarbon solvent with an anionic polymerizationinitiator; wherein said anionic polymerization initiator comprises acarbon lithio salt of the adduct of a cyclic secondary amine with aconjugated diene.
 2. A treadstock compound formed from the vulcanizableelastomer of claim 1.